164 lines
6.4 KiB
GDScript
164 lines
6.4 KiB
GDScript
extends Node3D
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## Dynamic fire: one noise signal drives the light rig AND the flame, so they pulse
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## together. Only the main light casts shadows.
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##
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## Design notes (see docs/FIRE-LIGHT.md):
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## - FastNoiseLite Perlin, two octaves: a slow "breathing" plus a fast flutter.
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## Never per-frame randomness and never switching the light off: hard toggling is
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## reported to make the lit area visibly "expand" after the switch.
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## - omni_range stays FIXED: animating the range makes the light boundary breathe.
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## - Frame-rate independent smoothing, so the flicker does not depend on FPS.
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## - The bounce light follows the documented fake-GI recipe for positional lights
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## (child of the main light, wider range, shadows off, specular 0, low energy).
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const MIN_ENERGY := 1.9
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const MAX_ENERGY := 2.8
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const BASE_RANGE := 10.0
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const SEED := 20261011
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## Perlin rarely reaches its extremes, so the raw sample is gained before clamping.
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const GAIN := 1.6
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const SLOW_HZ := 0.8
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const FAST_HZ := 7.0
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const SLOW_WEIGHT := 0.75
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const RESPONSE := 15.0
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## Bounce light: wider and dimmer, no shadows, no specular (fake indirect lighting).
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const BOUNCE_RANGE_FACTOR := 1.4
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const BOUNCE_ENERGY_FACTOR := 0.2
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const BOUNCE_SWING := 0.4
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## Hot core near the flame.
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const CORE_RANGE := 3.5
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const CORE_ENERGY_FACTOR := 0.45
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const CORE_SWING := 0.5
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## Very small, slow sway of the shadow-casting light: this is what makes the
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## shadows on the walls and floor move. Keep it subtle; large jumps look wrong.
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const JITTER := 0.04
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const JITTER_HZ := 1.2
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## Flame height breathing, in fractions of the flame quad height.
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const FLAME_SWING := 0.08
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var main_light: OmniLight3D
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var bounce_light: OmniLight3D
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var core_light: OmniLight3D
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var embers: CPUParticles3D
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var flame: CPUParticles3D
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var _flame_mesh: QuadMesh
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var _flame_material: StandardMaterial3D
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var _flame_height := 0.8
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var _noise := FastNoiseLite.new()
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var _time := 0.0
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var _pulse := 0.0
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func _ready() -> void:
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name = "FireLightRig"
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_noise.seed = SEED
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_noise.noise_type = FastNoiseLite.TYPE_PERLIN
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_noise.fractal_type = FastNoiseLite.FRACTAL_NONE
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_noise.frequency = 1.0
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main_light = OmniLight3D.new()
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main_light.name = "FireLight"
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main_light.light_color = Color(1, 0.36, 0.07)
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main_light.omni_range = BASE_RANGE
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main_light.omni_attenuation = 1.6
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main_light.omni_shadow_mode = OmniLight3D.SHADOW_CUBE
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# NOTA: in Compatibility il modo dual-paraboloid non e' supportato e l'engine
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# logga un errore saltando le ombre; solo SHADOW_CUBE funziona qui.
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main_light.shadow_enabled = true
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main_light.light_energy = (MIN_ENERGY + MAX_ENERGY) * 0.5
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add_child(main_light)
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bounce_light = OmniLight3D.new()
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bounce_light.name = "FireBounce"
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bounce_light.light_color = Color(1, 0.42, 0.12)
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bounce_light.omni_range = BASE_RANGE * BOUNCE_RANGE_FACTOR
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bounce_light.omni_attenuation = 1.5
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bounce_light.light_specular = 0.0
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bounce_light.shadow_enabled = false
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main_light.add_child(bounce_light)
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core_light = OmniLight3D.new()
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core_light.name = "FireCore"
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core_light.light_color = Color(1, 0.52, 0.16)
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core_light.omni_range = CORE_RANGE
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core_light.omni_attenuation = 1.4
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core_light.light_specular = 0.0
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core_light.shadow_enabled = false
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core_light.position = Vector3(0, -0.45, 0)
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main_light.add_child(core_light)
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_build_embers()
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_apply()
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## Links the flame emitter so its size and brightness follow the same signal.
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func attach_flame(particles: CPUParticles3D) -> void:
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flame = particles
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if particles.mesh is QuadMesh:
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_flame_mesh = particles.mesh
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_flame_height = _flame_mesh.size.y
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_flame_material = _flame_mesh.material if _flame_mesh else null
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## Bounded, smooth, deterministic flicker signal in [-1, 1]. Pure: same t -> same
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## value, which is what the tests sample without running frames.
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func pulse_at(t: float) -> float:
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var slow := _noise.get_noise_1d(t * SLOW_HZ)
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var fast := _noise.get_noise_1d(t * FAST_HZ + 137.0)
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return clampf((slow * SLOW_WEIGHT + fast * (1.0 - SLOW_WEIGHT)) * GAIN, -1.0, 1.0)
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func _process(delta: float) -> void:
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_time += delta
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# Frame-rate independent approach: no flicker speed change with FPS.
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_pulse = lerpf(_pulse, pulse_at(_time), 1.0 - exp(-RESPONSE * delta))
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_apply()
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func _apply() -> void:
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var midpoint := (MIN_ENERGY + MAX_ENERGY) * 0.5
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var span := (MAX_ENERGY - MIN_ENERGY) * 0.5
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var energy := clampf(midpoint + span * _pulse, MIN_ENERGY, MAX_ENERGY)
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main_light.light_energy = energy
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# Colour drifts less than brightness: a bigger shift reads as a colour cycling lamp.
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main_light.light_color = Color(1.0, 0.36 + 0.06 * _pulse, 0.07 + 0.05 * _pulse)
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bounce_light.light_energy = energy * BOUNCE_ENERGY_FACTOR * (1.0 + BOUNCE_SWING * _pulse)
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core_light.light_energy = energy * CORE_ENERGY_FACTOR * (1.0 + CORE_SWING * _pulse)
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main_light.position = Vector3(
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_noise.get_noise_1d(_time * JITTER_HZ + 11.0) * JITTER, 0.0,
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_noise.get_noise_1d(_time * JITTER_HZ + 71.0) * JITTER)
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if _flame_mesh:
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_flame_mesh.size.y = _flame_height * (1.0 + FLAME_SWING * _pulse)
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if _flame_material:
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var brightness := 1.0 + 0.25 * _pulse
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_flame_material.albedo_color = Color(brightness, brightness, brightness)
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func _build_embers() -> void:
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embers = CPUParticles3D.new()
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embers.name = "FireEmbers"
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embers.amount = 8
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embers.lifetime = 1.8
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embers.preprocess = 0.9
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embers.emission_shape = CPUParticles3D.EMISSION_SHAPE_SPHERE
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embers.emission_sphere_radius = 0.22
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embers.direction = Vector3.UP
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embers.spread = 22
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embers.gravity = Vector3(0, 0.35, 0)
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embers.initial_velocity_min = 0.5
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embers.initial_velocity_max = 1.2
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embers.scale_amount_min = 0.6
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embers.scale_amount_max = 1.2
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var ramp := Gradient.new()
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ramp.set_color(0, Color(1, 0.72, 0.25, 0.95))
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ramp.set_color(1, Color(0.7, 0.12, 0.02, 0))
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embers.color_ramp = ramp
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var spark := SphereMesh.new()
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spark.radius = 0.012
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spark.height = 0.024
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var material := StandardMaterial3D.new()
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# Unshaded on purpose: fire must not depend on scene lights (a light placed
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# inside a particle system lights it inconsistently), it emits its own glow.
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material.shading_mode = BaseMaterial3D.SHADING_MODE_UNSHADED
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material.transparency = BaseMaterial3D.TRANSPARENCY_ALPHA
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material.blend_mode = BaseMaterial3D.BLEND_MODE_ADD
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material.depth_draw_mode = BaseMaterial3D.DEPTH_DRAW_DISABLED
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material.vertex_color_use_as_albedo = true
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material.albedo_color = Color(1, 0.55, 0.2)
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spark.material = material
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embers.mesh = spark
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embers.cast_shadow = GeometryInstance3D.SHADOW_CASTING_SETTING_OFF
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embers.position = Vector3(0, -0.42, 0)
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add_child(embers)
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